This rule detects potential enumeration of Amazon Web Services (AWS) S3 buckets that may indicate reconnaissance activity by unauthorized users. The detection criterion is focused on events generated by the AWS CloudTrail service where the event source is 's3.amazonaws.com' and the event name is 'ListBuckets'. This particular API call is used to list all S3 buckets within the AWS account. The rule applies a filter that specifically looks for events where the user identity type is 'AssumedRole', which suggests that the AWS actions may be performed by an application or service assuming various IAM roles. It is noteworthy that the detection logic allows for legitimate administrators to be exempt from alerts, as they may need to run these commands as part of their normal operations.